The oxidation of depeptide azlactones is being studied in detail. The unsaturated azlactones resulting from the oxidation reactions will be used to prepare dehydro peptides having the amino acid sequences of renin substrate and the angiotensins I and II. The sites of unsaturation will appear at the peptide linkages normally cleaved by renin and converting enzyme so that cleavage will not occur. These dehydropeptides are potential inhibitors of the enzymes renin and converting enzyme.